Discuss
  • Resuming execution contexts

Resuming execution contexts

# Alan Schmitt (4 years ago)

Hello,

I am trying to understand how the resuming of execution contexts work. For instance, step 9 of tc39.es/ecma262/2021/#sec-generatorresume says "Resume the suspended evaluation of genContext using NormalCompletion(value) as the result of the operation that suspended it." I can see that the code to run would be the one created by step 4 of tc39.es/ecma262/2021/#sec-generatorstart, but I do not understand what the "using NormalCompletion(value) as the result of the operation that suspended it" means, as this code does not seem to take an argument.

Please let me know if this is not the right forum to ask such questions. And thanks a lot for any help you may provide.

Best,

Alan

# Logan Smyth (4 years ago)

as this code does not seem to take an argument.

The resumption state set by GeneratorStart does not take an argument because there is no way to access the first resumption value in a generator, though there is the function.sent proposal to allow that: tc39/proposal-function.sent

In the case you're asking about, the value applies in the case of GeneratorYield tc39.es/ecma262/2021/#sec-generatoryield which does take a resumption value argument.

# Alan Schmitt (4 years ago)

Hello,

On 2021-03-16 10:43, Logan Smyth <loganfsmyth at gmail.com> writes:

as this code does not seem to take an argument.

The resumption state set by GeneratorStart does not take an argument because there is no way to access the first resumption value in a generator, though there is the function.sent proposal to allow that: tc39/proposal-function.sent

In the case you're asking about, the value applies in the case of GeneratorYield tc39.es/ecma262/2021/#sec-generatoryield which does take a resumption value argument.

Thanks a lot for the clarification. So would it be correct to state that resumptions are always passed a value, but in some cases it is not used (the sentence there is "when evaluation is resumed for that execution context") and in other cases it is used ("when evaluation is resumed with a Completion completionName")? If so, could they be made uniform in the specification text (for instance, "when evaluation is resumed for that execution context with a Completion completionName")?

Thanks again,

Alan